The present invention relates to a multiplexer device for multiplexing multimedia data (media information) such as digitalized video signals, acoustical signals, and other data or the like. Multiplexed data is encoded to be transmitted or to be accumulated or for other purposes, and is applicable, as a concrete example of application, to a digital broadcasting system using satellites, ground waves, cables, or optical fibers, video on demand (VOD), and a teleconference system or the like.
FIG. 8 is a functional block diagram showing, as an example, a conventional type of multiplexing transmitting system described in the report of the Telecommunications Council in the Ministry of Posts and Telecommunications, Consultation No. 74:
xe2x80x9cTechnological conditions in a satellite digital broadcasting system (which uses a 27 MHz band width), said satellite using a band width in a range from 12.2 to 12.75 GHz in xe2x80x9cTechnological conditions according to a digital broadcasting systemxe2x80x9dxe2x80x99(July, 1995).
In FIG. 8, designated at the reference numeral at 1 is a video encoding section, at 2 a sound encoding section, at 3 a data encoding section, at 4 a multiplexing section, at 5 a transmission scramble section, at 6 an error correction encoding section, and at 7 modulating section.
Next description is made for operations of the multiplexing transmitting system based on the conventional technology.
In the video encoding section 1, sound encoding section 2, and data encoding section 3, a video signal 11, an acoustic signal 12, and various types of data signal 13 are subjected to information-source encoding respectively.
The multiplexing section 4 multiplexes a video encoded bit stream 14, a sound encoded bit stream 15, and data encoded bit stream 16 each generated according to the information source encoding for each packet and generates a multiplexed bit stream 17.
The transmission scramble section 5 performs energy dispersal to the multiplexed bit stream 17. The error correction encoding section 6 subjects a multiplexed bit stream 18 after the energy dispersal to error correction encoding. The modulating section 7 subjects a multiplexed bit stream 19 after the error correction encoding to modulation suitable for a transmission line and generates a transmission signal 20 in a specified frequency band.
Description is made for the multiplexing section 4 with reference to FIG. 9. In FIG. 9, the reference numeral 8 indicates a multiplexed additional information generating section for generating information indicating multiplexing and arrangement conditions or the like when each of the encoded bit streams 14 to 16 are multiplexed. Multiplexed additional information 21 such as PSI (Program Specific Information) specified in the ISO/IEC 13818-1 publication or SI (Service Information) specified in the European DVB (Digital Video Broadcasting) is generated by the multiplexed additional information generating section 8.
The packet multiplexing section 9 multiplexes the video encoded bit stream 14, sound encoded bit stream 15, data encoded bit stream 16 and multiplexed additional information 21 for each packet according to the multiplexed additional information 21 from the multiplexed additional information generating section 8 and generates a multiplexed bit stream 17.
The conventional type of multimedia multiplexing/transmitting system has the configuration as described above, which makes it difficult to multiplex information by flexibly using any band according to the priority in the information, for instance, by deciding the priority for each type of video and speech or the like and deciding the priority to any object appearing in the video and speech or the like, namely, a comparatively more amount of information is allocated to the information with the higher priority to be multiplexed while a comparatively less amount thereof is allocated to that with lower priority to be multiplexed.
Also, in the side where the multiplexed bit stream is received, it is difficult to edit and process the received information according to the priority or for each object.
Further, since information is not hierarchically classified into important information and not-important information to be transmitted, it is difficult to provide a function of stepped degradation; so called the function of graceful degradation in received information according to the quality of a transmission line.
It is an object of the present invention to enable multiplexing of information flexibly and efficiently by multiplexing the information according to the priority therein. It is another object of the present invention to realize multiplexer which has sufficient resistance to an error of transmission line and also has a function of graceful degradation.
A multiplexer device according to the present invention comprises a multiplexing means for multiplexing a plurality types of media information and outputting a multiplexed bit stream, a priority deciding means for deciding priority corresponding to each of the media information, and a multiplexing controller for controlling multiplexing of each of the media information according to the priority decided by the priority deciding means.
In the multiplexer device, the multiplexing means comprises a media multiplexer for multiplexing the plurality types of media information and generating a media multiplexed bit stream for each program, and a program multiplexer for multiplexing a plurality of the media multiplexed bit streams outputted from this media multiplexer and generating a program multiplexed bit stream, the priority deciding means decides priority for each of the media information as well as for each of the programs, and the multiplexing controller controls multiplexing of each of the media information by the media multiplexer according to the priority for the media information and also controls multiplexing of each of the media multiplexed bit streams by the media multiplexer according to the priority for the program.
The multiplexer device comprises a channel coder for subjecting the multiplexed bit stream outputted from the multiplexing means to channel coding according to the priority from the priority deciding means and transmitting the subjected multiplexed bit stream.
In the multiplexer device, the priority deciding means decides priority in each media information according to contents information corresponding to each of the media information, or decides priority in each program according to contents information corresponding to each of the programs.
The multiplexer device comprises a priority correlation table information generating means for generating both or one of information indicating association and priority between media information or between programs, and the multiplexing means multiplexes the priority correlation table information.
In the multiplexer device, the priority correlation table information comprises packet identifying information for discretely identifying the media information multiplexed for each packet, program identifying information for identifying each program, group identifying information indicating association between programs, and priority information indicating the priority.
In the multiplexer device, further, the priority information comprises priority information for each program and priority information for each media information constituting each program.
A multiplexing/transmitting method according to the present invention comprises the steps of deciding priority corresponding to a plurality types of media information, controlling multiplexing of each media information according to the decided priority, and outputting a multiplexed bit stream.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.